With the increasing use of electronic rather than photographic data collection, and on-line minicomputers at the telescope, two factors will necessitate a reconsideration of the way in which data are stored at the telescope.

1) Many of the electronic data collecting methods produce data in a final or semifinal (digital) form and usually with a large dynamic range; high-data-rate digital recording devices at the telescope are increasingly necessary.

2) Minicomputers allow quality control of data and often complete data reduction either in real time or with a very short time delay. We shall consider both these factors in some detail, emphasizing some of the many possibilities inherent in the increasing availability of one- and two-dimensional array detectors and mass storage devices. But let us first briefly examine the “classical” data gathering techniques. As in the later discussion, we shall subdivide the field into high-resolution spectroscopy, low-resolution spectroscopy (including multicolor photometry), surface photometry of extended objects, and positional astronomy.